1.Definition of refractive error
The refractive state of the two eyes is not the same, called refractive aberration (anisometropia). Generally speaking, there is a mild difference between the refractive states of the two eyes, and complete agreement is rare. There are various types of refractive aberrations. It can be manifested as a difference in the refractive properties of the two eyes, or a difference in refractive power between the two eyes with the same refractive properties. Clinical refractive error is divided into physiological and pathological, the difference between the refraction of the two eyes: spherical ≥ 1.50D, columnar ≥ 1.00D for pathological refractive error.
2, refractive aberration of the type
(1) Simple hyperopic (near) aberration.
One eye orthophoria, one eye hyperopia (myopia)
(2) Complex hyperopic (myopic) aberration.
Both eyes are farsighted or myopic, but the degree is not equal
(3) mixed parallax: one eye hyperopic, one eye nearsighted
(4) Simple astigmatism: one orthophoria, one astigmatism
(5) Compound astigmatism.
Both eyes are astigmatism of the same nature, but the degree is different
(6) mixed astigmatism: the two eyes have different nature of astigmatism
3.The causes of refractive aberration
In the process of eye development, the degree of hyperopia is decreasing, while the degree of myopia is developing. If the degree of farsightedness or myopia development progresses differently in the two eyes, it can cause refractive disparity.
In the case of congenital factors, there is an obvious imbalance in the development of the eye axis at birth and the refractive state of the two eyes is not symmetrical;
In addition, eye trauma, eye surgery can also cause refractive disparity.
4.Harm of refractive aberration
First, damage the monocular function of both eyes; second, lead to monocular amblyopia and exotropia
Myopic refractive aberration is not easy to form amblyopia, because patients often use a lighter myopic eye to see far, and a more myopic eye to see near. The nature of their gaze is generally central gaze or paracentral gaze, after refractive correction of vision can be improved, but if the refractive aberration is too large, the two eyes appear obvious unequal vision, the visual center is difficult to fuse the retinal image of both eyes, can not form binocular monovision, then the more myopic degree of one eye to form amblyopia.
5, refractive aberration correction methods
(1) frame glasses
(2) Contact lenses
Soft contact lenses (SL)
Rigid contact lenses (RGP)
Keratomileusis (OK)
(3) Intraocular refractive surgery
Posterior chamber IOL implantation for crystalline eyes (PIOL)
Clear lens removal + IOL implantation (RLE)
(4) Corneal refractive surgery
Laser refractive corneal surgery: Excimer laser surface keratomileusis (PRK), Excimer laser subepithelial keratomileusis (LASEK), Excimer laser in situ keratomileusis (LASIK), Excimer laser subepithelial keratomileusis (SBK), Femtosecond laser SBK (FS-SBK), Femtosecond laser stromal lenticule excision (SMILE)
Non-laser keratomileusis: radial keratotomy (RK), corneal stromal ring implantation (ICRS)